Great Northern Highway links Western Australia's capital city Perth with its northern most port, Wyndham. With a length of almost 3,200 kilometres, it is the longest highway in Australia, with the majority included as part of the Perth Darwin National Highway. The highway is constructed as a sealed, predominantly two-lane single carriageway, but with some single-lane bridges in the Kimberley. Great Northern Highway travels through remote areas of the state, and is the only sealed road link between the Northern Territory and northern Western Australia.